196

That would mean that all werewolves would eventually become extinct as they could not reproduce. Their lineage would be in constant decline.

Now, if you instead make it that only OLD werewolves can infect others you can have the same limit on sales with a reasonable excuse as to why they don't overrun the world from exponential growth. Something like it takes years of transformations before the infection can change their genetics enough to be passed along through a bite.